Your analysis is 100% correct. The fancy DAC is wasted. Get to the Xilica directly via a digital source, if you can.
The kind of exception to this rule is if you are using a DSP on a subwoofer only. Then the fancy upstream DAC is still worthwhile.
The kind of exception to this rule is if you are using a DSP on a subwoofer only. Then the fancy upstream DAC is still worthwhile.